In the sugar industry, sugar cane is typically crushed between rollers arranged in pairs or in groups of three. Generally, the rollers have a plurality of machined ridges extending circumferentially about the roller forming a surface of alternate ridges and valleys. The grooves are typically evenly spaced along the roller, however, it will be appreciated that in some applications, it may be desirable to have unevenly spaced grooves. The grooved arrangement provides for gripping of the sugar cane fibre as it passes between the rollers, the groove of an upper roller being operatively aligned with the ridges of its opposing lower roller or rollers.
A sugar mill roller is usually constructed as a cast roller mounted on a shaft and turned by drive means. Wear resistant material has on occasion been provided on the caps of the ridges of grooved rollers, but only at intermittent locations around the circumference of the roller. This approach has been taken partly because it was believed that the intermittent application of the abrasion resistant material produced the best gripping surface for the milling of sugar cane. Typically, conventional hardfacing material is used, including, for example, high speed steels, austenitic manganese steels, austenitic high chromium irons, cobalt or copper based alloys, or nickel-chromium-boron alloys according to the practices set forth in Jones, F D, & Horton, H L, Machinery's Handbook, ISBN 0-8311-1155-0. Additionally, abrasion resistant material such as chips of tungsten carbide, for example, may be laid up in the matrix to form a hardfacing composite in the hardfacing materials listed in this reference or in mild or stainless steel weld.
After a period of use, sugar mill rollers require refurbishment due to the hardfacing wearing smooth, causing slippage of the cane and/or bagasse between the rollers. In order to refurbish such a roller according to traditional practice the entire roller is removed from the mill, broken up and recast into a new roller. This approach is costly in terms of replacing the entire roller and requires a significant downtime for the sugar mill in having the roller replaced. There are also costs for heavy transport for removing and delivering the rollers to site.
The present invention aims to alleviate one or more of the above disadvantages and to provide a roller having a wear resistant surface and method of forming same which will be reliable and efficient in use.